1. Field of the Invention
The present invention generally relates to a device and a method for displaying residual capacity information of a smart battery, and more specifically, to a device and a method for exactly displaying an actual state of a residual battery capacity corresponding to a current battery level of a portable electronic device employing a smart battery.
2. Background of the Invention
Nowadays, rechargeable batteries are variously used for portable electronic devices such as portable computing systems, video cameras, and mobile phones. Those portable electronic devices include rechargeable batteries, e.g., smart batteries embedding microcontrollers therein. The microcontroller provides the portable electronic devices with various information items such as battery conditions, battery charge capacity, and a manufacturing company of the battery. Hence, the smart battery can provide information about its residual capacity to the portable electronic device so as to display a battery state relevant to the residual capacity of the battery.
There are various reasons to cause variations of residual capacity of a battery. For instance, when a user charges or discharges the battery with frequent times, or without full capacity, the charge capacity of the battery would be reduced.
As described above, while the smart battery has a function of offering the information on the residual amount of battery capacity, and it is required to exactly estimate the battery capacity changeable in accordance with various environmental elements in order to offer exact battery residual capacity information. Thus, the smart battery sets up a new reference capacity in accordance with the changes of battery capacity, and provides present residual capacity information based on the reference capacity. For the purpose of establishing the new reference capacity, the smart battery carries out calibration when an output voltage becomes lower than a predetermined level. The calibration is used for re-establishing the reference capacity of the battery with a measured value of a total charge capacity of a battery. During the calibration, a discharge starts from a full-charged state, and the amount discharged until the output voltage of the smart battery becomes lower than the predetermined voltage level is established as a reference capacity. In case that the battery continues to be discharged after the calibration, the reference capacity is set by performing a re-calibration after the former discharge is finished.
However, after a frequent charge or discharge, the smart battery may offer the battery residual capacity information having an error. A reason of erroneous information for residual capacity arises from an incorrect calibration not corresponding to an actual environment in use. In other words, since the calibration associated with a specific program, the residual capacity by the battery calibration is different from the actual residual capacity of the battery.
The foregoing drawbacks cause various problems in using the portable electronic device employing the smart battery because of wrong information for the battery residual capacity.
A process for displaying a battery residual capacity in a portable electronic device having the earlier smart battery is shown below. It is performed in a power management system installed in a portable computer.
The power management system of the portable computer system checks whether or not an alternating current (AC) adapter is installed. If there is no AC adapter, the system operates in a battery mode that provides a power source for the portable computer from the smart battery. Afterwards, the battery discharge starts, and battery information is received. In other words, the power management system detects a state of the battery by receiving battery relative state of charge (RSOC) from a microcontroller of the smart battery.
The power management system detects a state of low battery (LB) in which the battery residual capacity is reduced less than 10%, and displays a warning for a user through a liquid crystal display (LCD) panel. Then, if the smart battery continues to discharge, and thus a low low battery voltage is detected, i.e. if the battery residual capacity is reduced less than a predetermined amount, e.g., less than 3%, the power management system stores data by making an operating system (OS) program to protect current data at work. This case is called a low low battery (LLB) state. The OS program serves to support a power management function such as advanced power manager (APM) or advanced configuration and power interface (ACPI), and for instance, a WINDOWS type of OS (operating system) of the MICROSOFT Corporation belongs to the program. The OS program allows the data being processed of the present system to be stored in a hard disk drive, and after the operation, the power management system finishes the system by blocking the power source provided from the smart battery.
The battery discharge is stopped before the battery voltage gets to the level for the calibration, failing to carry out the calibration. In case the calibration is not accomplished, an accuracy of the data about the battery residual capacity is degraded. Further, even though the calibration is accomplished by the battery voltage getting to the calibration level, points of completing the discharge are respectively different, resulting in generating an error due to a re-calibration.
In general, a voltage level used for the calibration of the smart battery is present between LB and LLB. However, when a warning caused from LB is displayed, a general user connects the AC adapter to the portable computer system for charging the battery, or ceases using the system. Thus, the battery discharge is stopped before the battery voltage gets to the level for the calibration, failing to carry out the calibration. In case the calibration is not accomplished, an accuracy of the data about the battery residual capacity is degraded. Further, even though the calibration is accomplished by that the battery voltage gets to the calibration level, points of completing the discharge are respectively different, resulting in generating an error due to a re-calibration.
Like this, if it is impossible to correctly detect a state of LB or LLB because of the extreme difference in an accuracy for the battery residual capacity, the system may be turned off while the portable computer system is used, which may cause a loss of data. For instance, it is assumed that data value of the battery RSOC provided from the smart battery is more than LLB, even though the actual battery residual capacity is already less than LLB. Then the battery is fully discharged before an operation of save-to-disk is carried out, and the portable computer system is powered off. Thus, the data being processed may be lost. The portable computer system has a function to display the residual capacity of the smart battery in percentage for a user, but the error prevents the system from displaying the exact battery residual capacity for the user.
Exemplars of the art include U.S. Pat. No. 6,262,577 issued to Nakaoetal., for Method of Measuring Quantities Indicating State of Electrochemical Device and Apparatus for the Same, U.S. Pat. No. 6,222,370 issued to Schousek et al, for Universal Battery Monitor, U.S. Pat. No. 6,025,698 issued to Kim et al., for Smart Battery Charging System, Charging Method Therefor and Power Supply System for Portable Computer Using the Same, U.S. Pat. No. 4,709,202 issued to Koenck et al., for Battery Powered System, U.S. Pat. No. 6,081,154 issued to Ezell et al., for Circuit for Determining the Remaining Operating Life of a System, U.S. Pat. No. 6,078,871 issued to Anderson, for Method of Displaying a Status Condition of a Battery, U.S. Pat. No. 6,157,169 issued to Lee, for Monitoring Technique for Accurately Determining Residual Capacity of a Battery, U.S. Pat. No. 5,955,869 issued to Rathmann, for Battery Pack and a Method for Monitoring Remaining Capacity of a Battery Pack, and U.S. Pat. No. 6,265,848 issued to Mukainakano, for Battery State Monitoring Circuit and Battery Device.
It is, therefore, an object of the present invention to provide a device and a method for exactly displaying battery residual capacity information by detecting a difference between an actual residual capacity and a data value about residual capacity of a smart battery.
It is another object of the present invention to provide a device and a method for displaying a battery charge capacity by eliminating an error accompanied by residual capacities in stages of the battery relative state of charge.
It is yet another object to provide an inexpensive technique of accurately determining the battery charge capacity information.
It is still yet another object to provide a technique of determining the battery charge capacity information that is easy to implement.
In order to attain the above objects, according to an aspect of the present invention, there is provided a portable electronic device including a battery for providing a power source to the portable electric device, a control unit for controlling the device to display battery residual capacity information by receiving a relative state of charge (RSOC) from the battery, and a display unit for displaying the battery residual capacity information,where the control unit detects an output voltage of the battery, compares the detected voltage with the RSOC, and controls the device to display the battery residual capacity information in response to data corresponding to the detected voltage, when the battery is in a period of a first low battery and the detected voltage is different from the RSOC, or controls the device to display the battery residual capacity information in response to the RSOC when the battery is in a period of a second low battery lower than the first low battery.
In a preferred embodiment of the invention, the first low battery period is in a residual capacity state of 15xcx9c20% of full charge capacity of the battery, and the second low battery period is in a residual capacity state of 3xcx9c10% of the full charge capacity of the battery.
In the preferred embodiment of the invention, the control unit controls the device to store present data being processed, and to block the power source of the portable electronic device when the second low battery period is detected.
In the preferred embodiment of the invention, the control unit is formed of a microcontroller.
In the preferred embodiment of the invention, the control unit includes a function key for calling to display the battery residual capacity information, a microcontroller for receiving the RSOC from the battery, a basic input/output system (BIOS) for controlling and providing the RSOC to the microcontroller in response to the calling of the function key, and an operating system (OS) program for displaying the battery residual capacity information in response to the RSOC and a control provided from the microcontroller.
According to another aspect of this invention, there is provided a method for displaying battery residual capacity information of a portable electronic device including a battery, the method including the steps of receiving relative state of charge (RSOC) from the battery, identifying whether the battery is in a period of a first low battery from the RSOC, detecting a voltage of the battery when the battery is in the first low battery period, comparing the detected voltage with the RSOC, controlling the device to display the battery residual capacity information by using data corresponding to the detected voltage when the detected voltage is different with the RSOC, identifying whether the battery is in a period of a second low battery lower than the first low battery from the RSOC, and controlling the device to display the battery residual capacity information by using the RSOC when the battery is in the second low battery period.
In a preferred embodiment of the invention, the method further includes a step of controlling the device to store present data being processed of the portable electric device, and to block a power source of the portable electric device, when the battery is in the second low battery period.
As is apparent from the foregoing, the control unit displays exact battery residual capacity information in stages by correcting a variation between a relative state of charge (RSOC) and a detected voltage, in response to a low battery level or a low low battery level of the smart battery.